Organic-inorganic hybrid materials offer the opportunity to combine the desirable properties of organic polymers, such as, for example, processability, toughness, and impact strength, with the desirable properties of inorganic materials, such as, for example, high temperature stability, durability, and high modulus.
Silsesquioxanes are polymeric silicate materials of the type RSiO.sub.1.5 where R is an organic substituent. It is known how to synthesize silsesquioxane polymers containing reactive organic functional groups such as, for example, phenyl, chlorophenyl, vinyl, or methacryl. Additionally, polysilsesquioxanes with polystyrene arms have been synthesized by reacting polystyrene with silsesquioxane copolymers of phenyl with vinyl, methacryl, or chloropropylsilicate monomers. An especially attractive feature of silsesquioxanes is that they can be quite soluble and yet exhibit virtually complete condensation.
It is known that in situ polymerization of inorganic metal alkoxides, such as, for example, tetraethoxysilane, tetramethoxysilane and phenyltrimethoxysilane in organic polymers, such as poly(tetramethylene oxide), or poly(methyl methacrylate) can generate hybrid materials exhibiting at least one of the following desirable properties: higher modulus, higher yield stress, increased breaking stress, or increased glass transition temperature (T.sub.g).
Unfortunately, one of the difficulties with in situ polymerization is the shrinkage exhibited by the organic-inorganic hybrid upon drying and curing. The shrinkage has been attributed to the removal of solvent and to the continued reaction of the inorganic oxide network via condensation reactions which eliminate alcohol or water molecules. The severe stresses which develop during drying and curing frequently lead to cracking of the product material, thus limiting its potential usage for many applications. Further, there is a need to develop materials exhibiting thermal stability when exposed to high temperatures (&gt;than about 200.degree. C.).
It is highly desirable to produce high performance, high temperature materials. Organic-inorganic composites are generally not readily produced using high temperature organic polymers because of the difficulty of synthesizing high temperature polymers functionalized with trialkoxysilane moieties, as well as the difficulties associated with processing and characterizing the composites. Identifying common solvents for the organic polymer and the inorganic polymerization reaction can also be difficult. The discovery of alternative inorganic-organic polymers as well as materials with a high thermal stability is needed.